Traditionally in the operation of diesel engines it has been necessary to develop a sufficiently high enough compression within the engine's combustion chamber to generate the heat necessary to vaporize and ignite the fuel charge. In order to reduce the compression within the combustion chamber, use has been made of supplemental electrical fuel heaters, ignitors, or chemical combustion accelerators. Generally, diesel engines are operated at compression ratios of between approximately 16:1 to generally 23:1 using standard diesel fuels with greater compression ratios being necessary to combust lower cetane fuels.
Continuing efforts are being made to develop effective means for reducing the necessity for high compressions in diesel engines in order to save both in engine efficiency as well as to make such engines more reliable and longer lasting. As the compression ratio is decreased in a diesel engine, both the costs and maintenance are decreased.
Although some efforts have been made to reduce the operating compression ratios of diesel engines below 16:1, such efforts have generally required that the fuel charges be either preheated, subjected to supplemental heating within the combustion chamber, ignited such as by use of a glow plug or blended with costly more volatile chemical fuel additives which will ignite at lower temperatures.
In addition to the foregoing problems associated with the auto combustion of diesel, kerosene, gasoline and alcohol fuels, it is also necessary to maximize the efficiency of compression ignition engines so as to conserve fuel while obtaining optimum engine performance. There has been a great deal of effort directed to modifying the primary and supplemental combustion chamber designs as well as modifying other components of diesel engines in order to effect a complete mixing of fuel charges to promote more efficient ignition and thorough burning of the fuel. However, due to the need to achieve high ignition temperatures through compression of the air in the cylinder, together with the heat loss characteristics of prior art compression ignition systems, it has not been possible to auto combust such fuels at lower compression ratios without providing supplemental energy input or more expensive fuel ignition additives.